THE TERNARY SYSTEM Gd-Ge-Sn AT 600°C.

The isothermal section at б 00°C of the phase diagram of the ternary system Gd-Ge-Sn was constructed in the whole concentration range, based on X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The formation of two continuous solid solutions, GcijGe.j-jSn (x=0-4, structure type SmsGe41 Pearson symbol oP36, space group Pntna, д=7.8565(12)-?.040(2), 6 = 14.812(2)-15.552(3), c=7.7781(12)-8.201(2) A) and GdsGea-JSn* (x=0-3, structure type Мпіз, fiP16, a= 8.57 02(8)-9.03 06 (13), c=6.430 5(5)-6.5 941(10) A), and limited solid solutions based on the binary compounds GdllGel0 (6 at.96 Sn), GdSn, (5.5 at.96 Ge), Gdn, (2 at.96 Ge), GdSn2 (5 at.96 Ge), and GduSn (3.5 at.96 Ge) was established. Three following ternary compounds were found in the system at 600°C: GcGejSn«.». GdGeftTS_<).8SSn1.iS_x.ls, and GdjGeSn«,. The detailed crystal structures of two of them were refined on X-ray powder diffraction data: GdGe0JS_<).8SSnl.2S_l.U1 structure type ScCoft2SSilTS, o512, Стет, д=4.3206(4)-4.3035(4), 6=16.4824(15j-16.443 3(14), c=4.1270(4)-4.0961(4) A and Gd2Ge2.9lSnm, structure type GdjGej jjBi, oS32, Cmcnt, a=4.0445(6), 6=30.473(5), c=4.1694(6) A. The third compound, GdjGeSn, adopts the structure type NcLjGeSr. The crystal structures are closely related and are built from layers of Gd trigonal prisms centered by Ge atoms (or in part by Sn atoms) and square-mesh nets of Sn atoms (or in part Ge atoms), which alternate along the crystallographic direction [010]. Partial disorder of Ge and Sn atoms is observed. [ABSTRACT FROM AUTHOR]